Refractory lining



United States Patent 3,141,783 REFRACTORY LINING Ernest Paul Weaver, Pittsburgh, Pa., assignor to Harbisou- Walker Refractories Company, Pittsburgh, Pa., a corporation of Pennsylvania No Drawing. Filed Apr. 27, 1962, Ser. No. 191,403 9 Claims. (Cl. 10658) This invention relates to refractory linings, and more particularly to linings having special utility for oxygen converter vessels. I

In certain metallurgical processes, such as in the oxygen steel-making process which has been variously designated as the LD process, oxygen bessemer process, oxygen converter process or Kaldo process, the basic furnace structure is comprised of a metal skin or shell having a refractory lining interiorly thereof which defines the furnace space in which the process is carried out. Generally, the refractory lining of these oxygen steel vessels is comprised of an inner working lining of such as a "tar bonded, chemically bonded, or burned basic brick, an outer lining adjacent the inner wall of the metal shellusually of a burned magnesite brick, and an intermediate layer.

The intermediate layer is usually monolithic and is formed by such as ramming of a refractory composition. The intermediate layer can vary in thickness, depending on the vessel being lined and the operating parameters to which the lining is to be subjected. It has been suggested that the composition of the intermediate layer be a tar bonded ramming mix. An example of a prior tar bonded ramming mix, which would be usable to form this intermediate layer, is a dead burned dolomite or magnesite or mixtures thereof with additions of such as creosote and pitch.

When using such as the creosote and powdered pitch additions, some difliculty is encountered in actual installation of the intermediate layer. The pitch has a melting point typically in the range of 275 to 325 F. The creosote is liquid above about 84 F. Thus, when a pitch and creosote mixture is used in a ramming mix, it must be maintained at an elevated temperature prior to and during actual ramming.

Alternate carbonaceous materials which have been used to form bonds between the particles of dolomite and/or magnesite include a mixture of tar and pitch, a mixture of bunker vC oil and gilsonite and related like compositions and mixtures well known to those skilled in the art.

Some mixtures have been suggested which need be heated to only 100 to 120 F. to produce a mix which may be worked satisfactorily. However, even this 100 to 120 F. minimum temperature is diflicult to maintain and requires complicated auxiliary apparatus at an installation site. The situation is further complicated when creosote is used, since this material tends to volatilize excessively when heated about 120 F., thereby raising the possibility of explosion in a confined working area as well as undesirable irritation of the epidermis of perconnel in the area.

conventionally, the intermediate layer between the working and metal shell lining is rammed up after each course of the former. This procedure has raised still another difliculty in that if the temperature of the previously rammed composition drops below about 70 F. the material becomes still? and lumpy, thereby engendering unsatisfactory bonding between subsequent courses of rammed material. In fact, such a phenomena is in direct conflict with a desired monolithic intermediate layer.

Accordingly, it is an object of this invention to provide an improved refractory lining composition, which composition is particularly suitable for use in forming the intermediate layer of the lining of furnaces used in certain metallurgical processes.

It is still another object of this invention to provide an improved refractory lining mix of the tar bonded type, which mix is easily handled and worked at ambient temperatures.

And it is still another object of this invention to provide an improved readily worked tar bonded lining mix which maintains its fluidity and workability at ambient temperature conditions, thereby promoting the formation of a rammed monolithic entity.

Briefly, according to one aspect of this invention, a tar bonded refractory lining mix is provided which maintains fluidity and workability at temperatures above about 40 F. The ramming mix is comprised of a selected basic refractory aggregate, a carbonaceous bonding material, and a useful amount of a selected hydrogenated ester of either a long-chain organic acid or alcohol.

Some prior workers, confronted with the problem of workability of ramming mixes, have suggested various lubricating additives which would tend to maintain the fluidity of the ramming mix at lower temperatures. These have included such as petroleum jelly, which is alleged to film the discrete particles of basic aggregate, and such as kerosene, gasoline, turpentine, benzene and like petroleum derivatives which would tend to thin the selected tar bonding agent. Of course, such petroleum derivatives considerably increase the danger of explosion and fire. Others have suggested various aqueous wetting and dispersing agents which would facilitate the formation of colloidal suspensions or emulsions. It is well known to those skilled in the art that water is an undesirable constituent in mixtures with basic refractory materials because of undesirable hydration, and subsequent danger of cracking because of expansion.

According to this invention, it has been discovered that desirable flowability and plasticity can be achieved in a tar bonded refractory lining mix by the addition of a useful amount of certain hydrogenated long-chain hydrocarbons and mixtures thereof. An example of such preferred hydrogenated hydrocarbons is the material referred to as hydrogenated sperm oil. The chief constituents of sperm oil are well known to be cetyl palmitate, cetyl alcohol and esters of lauric, myristic and stearic acids. Hydrogenated sperm oil is sperm oil which has been hydrogenated to produce a wax-like material consisting essentially of the hydrogenated esters of the acids contained in the sperm oil. It has been found that very small quantities, up to about 1%, are compatible both physically and chemically with conventional tar bonding mixes, whereas paraflin-type waves in similar amounts do not produce the desired results and in fact appear to lack compatibility.

In test mixes, it was established that a preferred com: bination of a bonding mix for basic refractory aggregate would be liquid bonding pitch, creosote and hydrogenated sperm oil in the weight ratio of about 5:5 :05 and that the minimum amount of such a mixture, which should be added to a selected basic aggregate, was on the order of about 8%, by weight. The following table sets forth a typical mix, according to the invention.

3 Table I Composition: Percent Dead burned dolomite 60 Magnesite fines 40 Plus bonds- Liquid bonding pitch 4.46 Creosote 3.56 Hydrogenated sperm oil .48

8.50 Screen analysis:

Retained on 6 mesh 20 Passing 6 mesh, retained on 28 mesh 35 Passing 28 mesh 45 The foregoing mix was subjected to workability tests and the relative workability determined according to ASTM standard method C-181. At 70 F., the workability index according to this method was 14. The rammed density was found to be on the order of 183 to 185 pounds per cubic foot. Such a high density has heretofore been considered unobtainable in a rammed backup lining section using conventional mixes and ramming techniques.

A typical method of manufacture followed in the preparation of mixes according to this invention is as follows:

(1) The liquid bonding pitch is heated to about 250 F.

(2) The creosote and blown sperm oil are added and thoroughly blended.

(3) The mix of step 2 is cooled to about 120 F. and combined with pre-mixed basic refractory aggregate.

(4) The mix of step 3 is then packaged for subsequent use.

The mix which resulted exhibited good workability and plasticity down ot temperatures as low as 40 F. In typi. cal industrial metallurgical plants, ambient temperature conditions usually furnish all the heat required for the mix. And even if the ambient temperature should be slightly lower, very simple reheating to above 40 F. (which is just above freezing temperatures) will restore the desired workability.

Because of the excellent workability and plasticity of mixes according to this invention, they need not be supplied in granular or unconsolidated form, as has been typically the practice when dealing with conventional ramming mixes, in order to obtain good density during installation. The mix of this invention may be, formed into slabs and billets of the type and nature conventionally termed plastic refractories, which, at the fabrication site may be installed without tedious layer-by-layer ramming techniques. All that is needed is to merelydrop a quantity of the slabs or billets into place and then apply sufficient working as to knit the separate billets into a monolithic mass. Further, because of this same quality of excellent workability at low temperatures, with only minor pre-heating these same mixes acquire good flowability particularly adapted for refractory castingproceduresas for example, vibration casting.

Although the aggregate. material which is combined with the bonding agent of this invention can be substantially the same as that used in forming the brick of the, working lining, it is not necessary that it be of high purity material. In most instances, the aggregate portion can be on the order of about 60% of a coarser brickmaking graded size range with about 40% of fines. For example, dead burned dolomite and/ or magnesite in a selected graded size range is quite satisfactory.

While hydrogenated sperm oil is preferred because it is a commercially available material, we have found that most hydrogentaed esters of long-chain (C-8 to C22) hydrocarbons are satisfactory. The selected ester may be the result of the esterification of a C-8 to C22 alcohol with a lower alkyl acid (C-l to C5) or C-Z to C- dibasic organic acids. Likewise, it may be the result of esterification of long chain acids (C-8 to C22) with a lower alkyl alcohol, or it may be mixtures of the foregoing. However, the selected hydrogenated ester or mixture thereof must be comprised of only carbon, hydrogen, and oxygen atoms. Further, the selected hydrogenated ester should exhibit a somewhat waxy and solid consistency at about 40 F. The softening point should be no higher than about 120 F., and preferably about 70 F. (room temperature). It must be miscible with the selected carbonaceous bonding material in amounts up to about 1%.

The exact phenomenon, by which the hydrogenated ester addition of our invention allows workability at temperatures above 40 F., is not fully understood. However, it appears to homogeneously combine with selected carbonaceous bonding materials such as pitch, and to maintain them in a soft, rather plastic, but non-sticky state and to promote intimate mixing with selected refractory aggregates. Also, the hydrogenated ester addition appears to greatly reduce the usually expected creosote odor.

A lining fabricated of a mix according to the concepts of this invention fulfills the dual purpose of (1) protecting the permanent tank lining from contact with hot metal and slag, and (2) acting as a makeup joint which compensates for permanent dimensional changes in the tank lining, and warping of the metal shell as the result of long compaigns. The latter function assists in maintaim inga tight relationshipbetween the brick of which the working lining is fabricated, thus promoting more uniform wear. In addition, since the monolithic intermediate layer may be of the same general composition as the working lining, it may serve as the working lining for short periods in areas of severe wear-thus, further promoting the campaign life of the lining.

As noted above, the upper range of a useful amount of the hydrogenated Wax-like materials of this invention appears to be about 1%. Greater amounts appear to serve no useful purpose and, in fact, appear to sometimes retard the desired intimate association of such as bonding pitch and creosote or other selected carbonaceous bond materials.

Having thus described our invention in detail and with sufiicient particularity as to enable those skilled in the art to practice it, what we desire to have protected by Letters Patent is set forth-in the following claims.

I claim:

1. In unconsolidated basic refractory ramming mixes bonded with selected carbonaceous bond materials, which mixes consist essentially of about parts of basic refractory and up to about 8 parts, by weight, of the bond material, the improvement consisting essentially of said bond material including a compatible hydrogenated long chain hydrocarbon ester in a quantity suflicient to maintain fluidity and workability in the mixes. at ambient temperature conditions.

2. In tar bonded, basic refractory ramming mixes con: sisting essentially of a size graded, basic refractory aggregate and a carbonaceous tar bonding agent, there being up to about 8 parts, by weight, of the bonding agent per 100 parts, by weight, of the basic refractory aggregate, the improvement consisting essentially of saidrbonding agent including hydrogenated sperm oil in a quantity sufficient to maintain fluidity and workabilityin the mixes at ambient temperature conditions but in an amount not exceeding about 1 part, byv weight.

3. In tar bonded, basic refractory ramming mixes consisting essentially of a graded basic refractory aggregate and selected carbonaceous bond materials,there being up to about 8 parts, by weight, of the bonding material per 100 parts, by weight, of the refractory aggregate, the improvement consisting essentially of said bonding mixture consisting essentially of liquid bonding pitch, creosote, and hydrogenated long chain ester, the bonding pitch, creosote, and ester being presentin the weight ratio of about 55:05.

4. The basic refractory mix of claim 3 in which the hydrogenated ester consists essentially of hydrogenated sperm oil.

5. In unconsolidated basic refractory ramming mixes bonded with selected carbonaceous bond materials, said mixes consisting essentially of about 100 parts, by weight, of basic refractory and up to about 8 parts, by weight, of said bond materials, the improvement consisting essentially of said bond materials including compatible hydrogenated long chain hydrocarbon ester in a quantity sufficient to maintain fluidity and workability at ambient temperature conditions, said ester selected from the group consisting essentially of the result of the esterification or" an alcohol having from 8 to 22 carbon atoms with an acid of the group lower alkyl acids having from 1 to 5 carbon atoms and dibasic organic acids having from 2 to carbon atoms, esters the result of esterifying a long chain organic acid having from 8 to 22 carbon atoms with a lower alkyl alcohol, and mixtures thereof, said esters consisting essentially only of carbon, hydrogen, and oxygen atoms, said ester exhibiting a waxy consistency at about 40 F. and having a softening point no higher than about 120 F., said ester being miscible with said selected carbonaceous bond material in amounts up to about 1 part, by weight, based on the total weight of the bond material.

6. A tar bonded, basic refractory ramming mix consisting essentially of about 60 parts, by weight, of coarser mesh size dead burned dolomite, about 40 parts, by weight, of magnesite fines, and about 8 parts, by weight, of a tar bonding mixture, said tar bonding mixture consisting essentially of liquid bonding pitch, creosote, and

sufi'icient hydrogenated sperm oil to maintain fluidity and workability in the mix at ambient temperature conditions.

7. The ramming mix of claim 6 in which the screen analysis of the refractory aggregate is about as follows: 20 parts, by weight, on a 6 mesh screen, about parts, by weight, on a 28 mesh screen, and about parts, by weight, passing the 28 mesh screen.

8. A plastic refractory slab consisting essentially of about parts, by weight, of a coarser brickmaking graded size range of a basic refractory aggregate, and about 40 parts, by weight, of basic refractory fines, and up to about 8 parts, by weight, of a carbonaceous bonding mixture, said bonding mixture consisting essentially of liquid bonding pitch, creosote, and a quantity of hydrogenated sperm oil sufiicient to maintain fluidity and workability in the slab at ambient temperature conditions but in a quantity not exceeding about 1 part, by weight, of the bonding mixture.

9. A plastic refractory slab according to claim 8 in which the liquid bonding pitch, creosote, and hydrogenated sperm oil are present in a Weight ratio of about 5:5:0.5.

References Cited in the file of this patent UNITED STATES PATENTS 1,616,192 Marks Feb. 1, 1957 2,943,240 Martinet June 28, 1960 FOREIGN PATENTS 690,859 Great Britain Apr. 29, 1953 

1. IN UNCONSOLIDATED BASIC REFRACTORY RAMMING MIXES BONDED WITH SELECTED CARBONACEOUS BOND MATERIALS, WHICH MIXES CONSIST ESSENTIALLY OF ABOUT 100 PARTS OF BASIC REFRACTORY AND UP TO ABOUT 8 PARTS, BY WEIGHT, OF THE BOND MATERIAL, THE IMPROVEMENT CONSISTING ESSENTIALLY OF SAID BOND MATERIAL INCLUDING A COMPATIBLE HYDROGENATED LONG CHAIN HYDROCARBON ESTER IN A QUANTITY SUFFICIENT TO MAINTAIN FLUIDITY AND WORKABLILITY IN THE MIXES AT AMBIENT TEMPERATURE CONDITIONS. 